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How do you connect to a stretched-out heater hose when replacement isn't an option?

I am working on a car which has 3/4" molded heater hoses going to the heater core. Both of these hoses are swollen up to 7/8" ID, but do not feel squishy, and the ends at the heater core do not feel damaged, and no evidence of leakage there. There is no access to the heater core fittings to replace the hoses, unless the steering rack is removed (way too much work) or the car is raised on a lift, and accessed from below (unfortunately, I am not a shop and don’t have a lift).

The problem is that the opposite ends of these hoses are bad. One end goes to the cylinder head, and one end goes to the coolant crossover pipe. I already cut off 5½" of the hose going to the cylinder head, and want to cut off the molded 90° going to the crossover pipe. The hose is starting to crack and leak at the nipple on the crossover pipe.

Now I can obviously buy a 3/4" 90° cut-to-fit heater hose, and a length of 3/4" straight heater hose, but I am having difficulty finding a suitable fitting for going from 3/4" to 7/8". Online research indicates that 3/4" hose is equivalent to 19mm and 7/8" hose is equivalent to 22mm, and that 22mm is a hose size used in some boats, but not for automotive use. I could only find one company selling this fitting online, and it would cost about $76 with shipping for two of them, all the way from Taiwan.

Since I am not really interested in paying that much for two aluminum fittings, I’m looking for other ideas. One idea that I have seen floated online for this situation is to use copper pipe of both sizes, solder or braze them together, and then put a bead of solder or brazing alloy around each end to act as a lip. This seems like a lot of effort, though, so I am looking for other ideas. I own a hydra-swage, and have access to scrap refrigeration-grade copper pipe at work, so I could certainly manufacture such adapters if necessary.

Any suggestions on how to join new hoses to these existing hoses as cheaply and easily as possible?

The facts that the hoses have swollen and cracked at the ends mean that the hoses are worn and can rupture at any moment under pressure. If you cannot replace the entire hose yourself, pay somebody to do it. Cheaper than an overheated, blown engine.

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With a little ingenuity there is likely a solution somewhere in this catalog

3/4" copper pipe has a 7/8" outside diameter. There are reducers or threaded adapters that may accept an automotive 3/4" heater hose connector.

Is this the Daewoo? I have a hard time remembering how those hoses are routed but I have never had to remove a steering rack to service heater hoses.

I would never trust any piece of a 3/4 hose that has swollen to 7/8, but if you are decided on doing it I would think a visit to your local hydraulic hose makers would get you a 7/8 brass hose barb, a 3/4 brass hose barb, and a union for the 2.


This is the 2002 Daewoo Lanos. The heater hoses can be replaced easily from below, if you place the car on a lift. There is no access to the fittings from above, even with the engine disassembled. The steering rack is mounted on the firewall, and the heater core connections are under this.

You are right that the hoses should be replaced, and I am uneasy about reusing them, but don’t really have a choice, at least for now. Once I get the cylinder head back from being reconditioned, and put the car back together and it has run fine for a few months, I may very well take it to a professional mechanic and have the heater hoses replaced for peace of mind.

Back in the olden days I could take an old hose in and they would find something pre bent that after a little trimming or whatever it would work.

I should thing you would be able to put the car up on jack stands high enough to slide under on a sheet of cardboard to
do the job right.

Near me, there are always business throwing out oak pallets, a stack of those under each front wheel would also do the trick.